1. Field of the Invention
The present invention relates generally to a blow-molded plastic container designed to package beverages hot-filled into the container, and more particularly to a blow-molded container that is able to withstand the internal pressures and external forces exerted on the container during packaging, transporting, and handling.
2. Related Art
Blow-molded plastic containers are commonplace in packaging beverages and other liquid, gel, or granular products. Studies indicate that the configuration and overall aesthetic appearance of a blow-molded plastic container can affect some consumer purchasing decisions. For instance, a dented, distorted, or otherwise unaesthetic appearing container may provide the basis for some consumers to purchase a different brand of product that is packaged in a more aesthetically pleasing manner.
While a container in its as-designed configuration may provide an appealing appearance when it is initially removed from blow-molding machinery, many forces act subsequently on, and distort the as-designed configuration before the container is placed on the shelf. Plastic containers are particularly susceptible to distortion because they are continually being re-designed in an effort to reduce the amount of plastic required to make the container. This reduction of plastic can decrease container rigidity and structural integrity.
In the packaging of beverages, especially juice, blow-molded plastic polyethylene terephthalate (PET) containers are used in the so-called “hot-fill” process. The “hot-fill” process comprises filling the containers with liquid at an elevated temperature, sealing the containers, and then allowing the liquid to cool. As a result of “hot fill” processing, internal forces (e.g., changes of pressure and temperature) act on the container and may cause distortion of the container. Therefore, hot-fillable plastic containers must provide sufficient flexure to compensate for these changes, while maintaining structural integrity and aesthetic appearance. The flexure is most commonly addressed with vacuum flex panels positioned under a label below the dome.
In addition to internal forces acting on the container, external forces may also be applied to sealed containers as they are packed and shipped. Filled containers are typically packed in bulk in cardboard boxes, or plastic wrap, or both. A bottom row of packed filled containers is likely to support several upper tiers of filled containers, and potentially, several upper boxes of filled containers. Therefore, it is important that the containers have a top loading capability that is sufficient to prevent distortion from the intended container shape.
The containers have exhibited a limited ability to withstand top loading during filling, capping and stacking for transportation. Overcoming these problems is important because it would decrease the likelihood of a container's top or shoulder being crushed, as well as inhibiting ovalization in this area. It is important to be able to stack containers so as to maximize the use of shipping space. Due to the weight of liquid-filled containers, the boxes often need reinforcing such as egg crate dividers to prevent crushing of the containers. The vulnerability of the containers to crushing can be increased by the deformation resulting from the above-mentioned vacuum.
A particular problem which can result from the hot-filling procedure is a decrease in the container's ability to withstand top loading during filling, capping and labeling. Because of the decreased container rigidity immediately after filling and after cooling, even heat set containers are less able to resist loads imparted through the top or upper portion of the container, such as when the containers are stacked one upon the other for storage and shipping. Top loads are imparted to the container when it is dropped and lands on the upper portion or mouth of the container. As a result of this top loading, the container can become deformed and undesirable to the consumer.
Dome region ovalization is a common distortion associated with hot-fillable, blow-molded plastic containers. The dome is the upper portion of the container adjacent to the finish. Some dome configurations are designed to have a horizontal cross-section that is circular in shape. The forces resulting from hot-filling and top loading can change the intended horizontal cross-section shape, for example, from circular to oval.
An example of hot-fillable, blow-molded plastic containers that can withstand the above-referenced forces and can maintain their as-designed aesthetic appearance are the containers disclosed in U.S. Pat. Nos. 5,762,221, D.366,416, D.366,417, and D.366,831 all assigned to the assignee of the present application. The referenced utility patent discloses a “bell-shape” dome located between a finish and label mounting area which controls the degree of dome deformation due to hot-filling and resists dome deformation due to top loading. The dome comprises stiffening structures formed by inwardly concave grooves that provide a degree of reinforcement against distortion of the dome. The referenced design patents illustrate in phantom lines a similar “bell-shape” dome whose diameter of the horizontal cross-section increases as the dome extends downwardly from the finish. The dome diameter then decreases into an inwardly extending peripheral waist, and downwardly from the waist, the dome diameter increases before connecting with the label mounting area of the container. The bell-shape of the dome provides an aesthetic appearance as initially blow-molded, and it also provides a degree of reinforcement against distortion of the dome, particularly ovalization types of distortion.
Containers of the above type have exhibited a limited ability to withstand top loading during filling, capping and stacking for transporting of the containers. Overcoming these problems is important because it would decrease the likelihood of a container's top or shoulder being crushed, as well as inhibiting ovalization in this area. Obviously, it is important to be able to stack containers so as to maximize the use of shipping space. It also enhances the ability to lightweight the container.
Embodiments of the present invention in contrast, allow for increased flexing of the vacuum panel sidewalls so that the pressure on the containers may be more readily accommodated. Additionally, the container is provided with a more circular cross-section that can increase an internal volume of the container and allow for a wide variety of labeling options.